Compositions and methods for treating doxorubicin, paclitaxel, or multidrug-resistant tumor cells are provided. The compositions include a doxorubicin-peptide conjugate as well as peptide coadministered with doxorubicin. The compositions of this invention also include a paclitaxel-peptide conjugate as well as peptide coadministered with paclitaxel. The conjugate compositions, as well as the coadministration therapy, will be useful in treating both patients with doxorubicin, paclitaxel, or multidrug-resistant cancer and those with normal cancer. The compositions of the invention are also more effective, and require smaller doses, than the chemotherapy agent alone because the peptide serves to target the chemotherapy agent to the tumor cells.
Doxorubicin is the most commonly used anticancer chemotherapeutic agent, and it has the widest spectrum of antitumor effects. Nagy et al., Cytotoxic analogs of luteinizing hormone-releasing hormone containing doxorubicin, PNAS 93:7269-7273 (1996). It is an anthracycline derived from Streptomyces peucetius var. coesius. Stan et al., Antineoplastic Efficacy of Doxorubicin Enzymatically Assembled on Galactose Residues of a Monoclonal Antibody Specific for the Carinoembryonic Antigen, Cancer Res. 59:115-121 (1998). It is has two regions, named adriamycinone and daunosamine. The structure of doxorubicin is shown in FIG. 1. Doxorubicin (xe2x80x9cDoxxe2x80x9d) intercalates itself into double-stranded nucleic acids, inhibiting DNA and RNA synthesis, and affects the stability of DNA-topoisomerase II complexes. In order to be effective, Dox must accumulate in the cell and reach certain threshold levels.
Paclitaxel is a common chemotherapeutic agent often used to treat breast cancer. It is distributed by Bristol-Myers Squibb under the tradename TAXOL(trademark). It is a natural product with antitumor activity. It is obtained via a semi-synthetic process from Taxus baccata (the Pacific Yew Tree). The chemical name for paclitaxel is 5xcex2,20-Epoxy-1,2xcex1,4,7xcex2,13xcex1-hexahydroxytax-11-en-9-one 4,10-diacetate 2-benzoate 13-ester with (2R,3S)-N-benzyol-3-phenylisoserine. The structure of paclitaxel is shown in FIG. 2.
Paclitaxel acts as an antimicrotubule agent by promoting the assembly of microtubules from tubulin dimers and stabilizing microtubules by preventing depolymerization. This stability results in the inhibition of the normal dynamic reorganization of the microtubule network that is essential for vital interphase and mitotic cellular functions. In addition, paclitaxel induces abnormal arrays or xe2x80x9cbundlesxe2x80x9d of microtubules throughout the cell cycle and multiple arrays of microtubules during mitosis.
The most significant problem oncologists face in the treatment of cancer, is the existence of drug resistance in tumors resulting in decreased cytotoxicity of chemotherapy agents. Some cancers are drug resistant prior to treatment, whereas others develop drug resistance during treatment.
In many instances, when a tumor develops drug resistance in response to treatment with one agent, such as Dox or paclitaxel, cross-resistance develops to structurally and functionally unrelated drugs such as vinblastine and cisplatin. Choudhuri et al., Reversal of resistance against doxorubicin by a newly developed compound, oxalyl bis(N-phenyl)hydroxamic acid in vitro, Anti-Cancer Drugs 9:825-832 (1998). This pattern of resistance is named multidrug resistance (MDR). Researchers have identified a gene MDR1, and its gene product, p-glycoprotein, in MDR tumors. P-glycoprotein functions as an efflux pump, preventing accumulation of drugs and hence reducing cytotoxicity. This mechanism is responsible for one type of doxorubicin resistance in cancer cells. Rahman, Modulation of Multidrug Resistance in Cancer Cells by Liposome Encapsulated Doxorubicin, J. Liposome Res. 4:575-604 (1994).
Paclitaxel is a substrate for the multidrug resistant pump, which is also termed gP170, and cells selected for high levels of resistance to this drug have increased levels of gP170. Gonzalez-Garay, A xcex2-Tubulin Leucine Cluster Involved in Microtubule Assembly and Paclitaxel Resistance, J. Biol. Chem. 274:23875-23882 (1999). Other paclitaxel resistance mechanisms have also been proposed including changes in the expression of specific xcex2-tubulin genes and mutations in xcex2-tubulin. Id.
Other mechanisms for chemotherapy resistance include: glutathione tranferances and detoxification mechanisms; topoisogenetic recombination, DNA transcription, chromosome segregation; and DNA repair. Harris et al., Mechanisms of Multidrug Resistance in Cancer Treatment, Acta Oncological 31:205-213 (1992).
Researchers have experimented with numerous different strategies for overcoming doxorubicin resistance. One such strategy involves the use of nonionic amphipathic diesters of fatty acids or a reverse poloxmer to treat MDR cancer. U.S. Pat. No. 5,681,812. Oligonucleotides specifically hybridizable with nucleic acids encoding MDR associated proteins have also been developed. U.S. Pat. No. 5,807,838. An hydroxamic acid derivative, oxalyl bis(N-phenyl)hydroxamic acid, has also shown promising results in reversing MDR. Choudhuri et al., Reversal of Resistance Against Doxorubicin by a Newly Developed Compound, Oxalyl Bis(N-phenyl)hydroxamic Acid in Vitro, Anti-Cancer Drugs, 9:825-832 (1998). Another strategy proposes the use of liposome encapulated doxorubicin to overcome doxorubicin resistance. Rahman, Modulation of Multidrug Resistance in Cancer Cells by Liposome Encapsulated Doxorubicin, J. Liposome Res. 4:575-604 (1994).
Doxorubicin conjugates have also been developed. Doxorubicin conjugated to a gallium-transferrin compound has been shown to reverse drug resistance in breast cancer cell lines. Yang et al., Reversal of doxorubicin resistance by doxorubicin-gallium-transferrin conjugate in human breast cancer cell lines, Proc. Am. Assn. Cancer Res. 40:4377 (1999). Analogs to luteinizing hormone-releasing hormone (xe2x80x9cLH-RHxe2x80x9d) have also been conjugated to doxorubicin, resulting in a more potent, targeted anticancer agent for tumors that possess receptors for LH-RH. Nagy et al., Cytotoxic Analogs of Luteinizing Hormone-Releasing Hormone Containing Doxorubicin or 2-Pyrrolinodoxorubicin, a Derivative 500-1000 Times More Potent, PNAS 93:7269-7273 (1996). Monoclonal antibodies have also been conjugated to doxorubicin, resulting in more potent treatment compositions. Stan et al., Antineoplastic Efficacy of Doxorubicin Enzymatically Assembled on Galactose Residues of a Monoclonal Antibody Specific for the Carcinoembryonic Antigen, Cancer Res. 59:115-121 (1999).
While doxorubicin conjugates have been considered previously, the art has taught away from derivatization of the amino group of the doxorubicin on the adriamycinone moiety. Neutralization of the dausonamine nitrogen of doxorubicin has previously resulted in severe loss of cytotoxic activity. See Nagy, Cytotoxic Analogs of Luteinizing Hormone-Releasing Hormone containing doxorubicin or 2-pyrrolinodoxorubicin, a derivative 500-1000 times more potent, PNAS 93:7269-7273 (1996); Zunino et al., Interaction of Daunomycin and its Derivatives with DNA, Biochim. Biophys. Acta 227:489-498 (1972). Such a modification was thought to inactivate the doxorubicin. Instead, those in the art have followed a strategy more difficult to accomplish involving modification of the CH2OH group in the adriamycinone portion of doxorubicin.
A previous paclitaxel-peptide conjugate has been constructed with a bombesin/gastrin-releasing peptide receptor-recognizing peptide: Gln-Trp-Ala-Val-Gly-His-Leu (SEQ ID NO: 8). Safavy, Paclitaxel Derivatives for Targeted Therapy of Cancer: Toward the Development of Smart Taxanes, J. Med. Chem. 42:4919-4924 (1999).
It is an object of the present invention to provide a method for treating a patient suffering from cancer, wherein a cancer chemotherapy agent is selected, conjugated to a peptide, and administered to the patient.
It is a further object of the invention to provide a method of treating a patient suffering from cancer, wherein a cancer chemotherapy agent is selected, a peptide is selected, and the agent and peptide are coadministered to the patient.
It is a further object of the invention to provide a composition for treating a patient suffering from cancer, wherein the composition comprises a chemotherapy agent and a peptide.